1. Field of the Art
The present invention relates to the field of storage area networks, and more specifically to a method and apparatus for passing data input/output (I/O) operations between host computers and storage subsystems, using Fibre Channel and Small Computer System Interface (SCSI) interfaces.
2. Description of the Related Art
In many data processing centers, it is common for data to be stored on storage units such as permanent storage drives, each of which is part of a large infrastructure of storage arrays or subsystems. Individual hosts, part of banks of such computers, located within the premises, or situated remotely, can be interconnected in complicated arrangements to utilize that storage, often via a storage area network (SAN). Interstitial devices, a storage router being an important example, can form the nodes of such a network, and play an important intermediary role in the communicative coupling between such elements.
For a host, an individual storage drive member is address-referenced by its logical unit number (LUN), which is generally the deepest level field of a multi-faceted address description, otherwise referred to as a hardware path. Other number fields comprising this description can include target, bus, port, area, protocol, adapter and bus-converter designations. Different hosts will have different requirements which will determine a hardware path description that is complete.
Configuration schemes can be established defining particular relationships amongst particular storage drives or between them and the individual hosts which must access them. Various forms of drive redundancy may be implemented, or perhaps other patterns of alliance, otherwise referred to as zoning, where elements of shared storage are made private to certain host members, for example.
Processes of this kind, involve customization of the drive address mappings, with redefinition of LUNs being a fundamental aspect of such processes. Typically, the redefinition of LUNs can be arranged through a user interface that provides the functionality necessary for the components which, in turn, provide a platform for management of the entire SAN and its attached elements. Ideally, this management platform is SAN-centric, and can be found in the storage routers, although such a management platform can alternatively reside as an integral part of the storage media, or within one or more of the hosts. However, it is often desirable to support legacy systems using newer technology, including the protocols associated with each (e.g., including the addressing schemes used therein). Unfortunately, such protocols are not always compatible, and these incompatibilities need to be addressed in order to allow for such support.